Squeaky brake system following emergency stop

[Sahara]

Had to brake very hard in an emergency situation today, about six hours ago. Since, there's been a loud squeak, only audible when the car is off (it's either quieter when the wheels are spinning or being drowned out by motor), that comes from the front of the car when the brake pedal is depressed. It's either coming from the brake master cylinder/booster or the calipers themselves. It is not coming from the pedal I believe. 

 

Some unique complicating factors are: 

 

New pads on both sides, new caliper on one side. Less than 200 miles on them. 

 

I suspect that the panic breaking did some very aggressive bedding of the new pads and got the calipers and rotors got filthy and the debris is causing the squeak. That or a crap-load of heat build up. Pedal feel and breaking action are normal. Also possible that I burned off all the grease down there. 

[dlacey]

could be a stone stuck in a dust shield...can often be fixed by reversing and braking to spit the stone out

[Sahara]

Just now, dlacey said:

could be a stone stuck in a dust shield...can often be fixed by reversing and braking to spit the stone out

Wouldn't that require the car to be in motion to make a sound? 

[Chris_B]

Seems like it could only be coming from the booster. Maybe something popped when you hit the brakes. You need to find a helper (or a proper length board) to depress the pedal and get under there with a stethoscope or a paper towel tube and determine the source.

 

[dlacey]

30 minutes ago, Sahara said:

Wouldn't that require the car to be in motion to make a sound? 

But what does "when the car is off" mean? I thought rolling, engine off...?  If the engine is switched off and car stationary then ?

[Sahara]

Just now, dlacey said:

But what does "when the car is off" mean? I thought rolling, engine off...?  If the engine is switched off and car stationary then ?

That is when the noise is most perceptible. When the car is stationary and the motor off. It's not coming from the actual action of the pads against the spinning rotors, it must be happening somewhere further up the chain. 

[Chris_B]

Seems like it could only be coming from the booster. Maybe something popped when you hit the brakes. You need to find a helper (or a proper length board) to depress the pedal and get under there with a stethoscope or a paper towel tube and determine the source.

[PaulTWinterton]

Start with the easy solution first.   Pop out your pads and apply a new layer of anti-squeal on the backside.  Replace the pads and go for a drive.  It may be that simple. 

Edited August 2, 2019 by PaulTWinterton

[Chris_B]

It seem like he is saying that the noise occurs when the car is not moving.

[PaulTWinterton]

12 hours ago, Sahara said:

when the brake pedal is depressed.

 

 

10 hours ago, Chris_B said:

It seem like he is saying that the noise occurs when the car is not moving.

 

Wasn't 100% positive about that in his post.  I guess we'll see.

 

Edit: I guess I didn't read a prior post.  Hmmm.

Edited August 2, 2019 by PaulTWinterton

[Mike Self]

Didja check all the pivot points on the linkage between the pedal and the booster (in the engine compartment).  There are several that transmit the force from the pedal forwards and upwards to the pushrod that activates the brake booster...try a little lubricant on them and see what happens.

 

mike

 

 

[PaulTWinterton]

This is a strange one.  Car off, motionless, press the brake pedal and get a squealing sound. Lubricate everything as Mike says, except pad faces.

 

How is the fluid level in the reservoir?  Could it be the action of fluid compressing/moving in the system, causing a harmonic vibration/squeal?  If you can pinpoint it to a caliper or at least a corner, maybe a bleed would help.  At least you might get another clue with fluid freely moving from the caliper.

 

I still say add more anti-squeal paste to the backside of the pads.  Maybe there is a freak force between pistons and pad causing the harmonic vibration and subsequent squeal.

['76mintgrün'02]

we need a video of this one.

[Dudeland]

Didja check all the pivot points on the linkage between the pedal and the booster (in the engine compartment).  There are several that transmit the force from the pedal forwards and upwards to the pushrod that activates the brake booster...try a little lubricant on them and see what happens.

 

mike

 

 

That is likely your problem. There is a pivot point that has a bolt going though a sleeve. I had to take mine out. I.E sells a ball bearing pivot. I got one but found it impossible to install. This will be something I address when the motor comes out.

 

You will need to remove the bolt and sleeve completely. Spraying it will not penetrate all the way into the middle, and want fix the squeak.

 

 

 

 

Sent from my iPhone using Tapatalk

[TobyB]

On 8/2/2019 at 8:58 AM, mike said:

Didja check all the pivot points on the linkage between the pedal and the booster (in the engine compartment).  There are several that transmit the force from the pedal forwards and upwards to the pushrod that activates the brake booster...try a little lubricant on them and see what happens.

 

mike

 

 

I'm with Mike, too,

 

Or the pads themselves are moving just a bit, and squeaking.  Disc brakes are self- adjusting based on

pressure, so a panic stop will reseat the seals further out, changing the relative movements ever so slightly.

 

hth

 

t